pandas.expanding_apply(arg, func, min_periods=1, freq=None, center=False, time_rule=None)

Generic expanding function application

Parameters :

arg : Series, DataFrame

func : function

Must produce a single value from an ndarray input

min_periods : int

Minimum number of observations in window required to have a value

freq : None or string alias / date offset object, default=None

Frequency to conform to before computing statistic

center : boolean, default False

Whether the label should correspond with center of window

time_rule : Legacy alias for freq

Returns :

y : type of input argument